Crankcase scavenging scoop



' H. c. HILL ET AL I 7, 0 CRANKGASE SCAVENGING SCOOP Nov; 22, .1938.

Filed June 13, 1936 v 2 Sheets-Sheet l 4 r Y INVENTORS Henry CHI/1 a Arthur Landauer TTORNFY.

Patented Nov. 22, 1938 UNi'lE s'rArss 2,137,400 CRANKCASE SCAVENGING sooor Henry G. Hill, Paterson, and Arthur Landauer, Itidgewood, N. .J., assignors to Wright Aeronau tioal Corporation, a corporation of New York Application June 13, 1936, Serial No. 84,994

3 Claims. (Cl. 134-45) This invention relates to scavenging of oil from engine crankcases and the like and more specifically, to means for improving the oil scavenging on radial aircraft engines.

These engines have outside oil tanks and separate pump systems, one for taking oil from the tank and delivering it under pressure to the engine bearings, while the other system returns oil from the crankcase or oil sump to the tank.

As the power and speed of engines has increased, there has been an increase in the oil flow required, which in large engines will now be of the order of 50 lbs. per minute. The crankcase of a radial engine is almost filled with the rotating crankshaft, counterweights and connecting rods, which create a violent state of turbulence which is enhanced by the displacement effect of the pistons on the vapor within the crankcase.

Accordingly, considerable difficulty has been experienced in obtaining satisfactory scavenge. Little difficulty is found at moderate speeds where the gravitational effects on the oil are effective to drain it to the intake of the scavenge pump or pumps. At high speeds however, the crankcase contents appear to comprise atomized. oil which is Whirled around to the defeat of gravitational drainage, and where the scavenging or drainage holes comprise only a smallpercentage of the circumference of the crankcase, scavenging failure is often experienced, so that the crankcase loads up with oil whereupon the hydraulic churning losses have been known to reach as high as 100 hp. and the oil temperature rise becomes excessive.

Some amelioration of these conditions has been obtained by means of a large number of scavenging holes placed around the crankcase walls whereby the contents may be passed. to the next adjacent sections wherein the conditions are relatively quiescent so that the atomized oil mass has a chance to settle down by gravity for flow to the scavenge pumps.

Further experimentation has indicated that the oil laden vapor in the case is in a state of rotation and, by means of a suitable scoop, such as forms the essence of this invention, it has beendemonstrated that a cure for these scavenging troubles has been obtained.

The preferred form of scoop here shown is particularly adaptable to a crankcase having opposed drain holes in its front and rear walls, but it will be obvious to those skilled in the art that the invention may be adapted to other dispositions of drain hole.

Other objects of the invention will be obvious from; or will be pointed out in, the following description with reference to the drawings, in

which:

Figure 1 is an axial fragmentary section thru' an engine crankcase embodying the invention.

Figure 2 is a fragmentary section on the line 2--2 of Figure 1.

Figure 3 is a detail section on the line 33 of Figure 1.

In these drawings, Iii, l2 designate respectively the rear and front bearing support walls of a conventional crankcase in which a conventional crankshaft, in general designated by I4, is mounted in the usual way. The crankcase walls are provided with holes it, it communicating with passages 26, 22 in auxiliary crankcase members 23, 25 which in turn communicate with the connections 26, 26 of an oil sump indicated as to its top portion only, by the reference numeral 28. The crankcase isequipped with theusual cylinders, two of which are indicated fragmentarily by the reference numeral 3!! (Figure 2).

It will be seen that these cylinders have projections 34 extending into the crankcase and. that these projections almost abut.

The form of scoop applicable to this particular design comprises the tubular ended member 36 which is cut down at its central portion 33 to a triangular section to clear the cylinder extensions and. is provided with wings it, brought as closely as possible to crankshaft counterweights 42, the ends of the member 36 engaging within. the holes l6, IS. The tubular end portions of the scoop are provided with drain ports M facing against the direction of rotation, into which ports the oil caught by the wings ii! is delivered for flow thru the tubular ends into the drainage passages 26, 22 and so into the sump.

The operation of the device is as follows: Due to the rapid rotation of the crankshaft i4, 42 and its associated parts, the oil in the crankcase is highly atomized and is in a state of violent rotational turbulence, whereby it may be driven past said drain ports M causing a failure to drain into the sump. By inclusion of the dam comprised by the wings fili rotation of this oil is arrested and the shape of the wings is such that the dynamic forces set up assist in feeding the oil into the ports M and. so into the sump.

It will be understood that the specific form of detachable cross tube with wings and ports is merely one embodiment of the invention suited for addition to a specific existing engine, wherein it has proven of value in improving the scavenging. Many other detail constructions are intended to be within the scope of the invention.

For instance, certain crankcases have integral cross ribs and it has been found that by forming these ribs to closely conform to the exterior of the crankshaft, and by drilling holes on the side of these ribs against which the oil splashes, beneficial results have also been obtained.

While we have described our invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding our invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. We aim in the appended claims to cover all such modifications and changes.

What is claimed is:

1. The combination with an engine having a crankcase and cylinder barrels projecting therein, said case having opposed scavenge holes in respective walls thereof, a tube engaged in said holes and passing between said barrels, and scoops defining lateral openings in said tube placed against the direction of rotation of the parts in said crankcase for the entrainment of oil in said tube.

2. In a radial cylinder engine comprising a crankcase and cylinder skirts extending there- Within, means for minimizing rotational turbulence, and for increasing the scavenging, of contained oil vapor comprising a device held between adjacent cylinder skirts, wings on said device extending inwardly of the skirts into the turbulent zone, and conduits leading from said wings to a portion of the crank case remote from the zone of turbulence.

3. In a radial cylinder engine comprising a crankcase containing, during operation, turbulent oil vapor, and cylinder skirts projecting therewithin, means for improving the scavenging of oil vapor contained within the crankcase during engine operation comprising wings held adjacent the cylinder skirts, and duct means at the outer portions of said wings to conduct oil entrained by said wings from the turbulent zone of said crankcase.

HENRY C. HILL. ARTHUR LANDAUER. 

